Flarum\Foundation\Application::loadDeferredProvider PHP Method

    public function loadDeferredProvider($service)
    {
        if (!isset($this->deferredServices[$service])) {
            return;
        }
        $provider = $this->deferredServices[$service];
        // If the service provider has not already been loaded and registered we can
        // register it with the application and remove the service from this list
        // of deferred services, since it will already be loaded on subsequent.
        if (!isset($this->loadedProviders[$provider])) {
            $this->registerDeferredProvider($provider, $service);
        }
    }